Nano Photometer Methods

OD600 Cell Density

The method OD 600 is used to determinate the absorbance at 600 nm. Bacterial cell cultures are routinely grown until the absorbance at 600 nm (known as OD600; default setting) reaches approximately 0.4 prior to induction or harvesting. A linear relationship exists between cell number (density) and OD 600 up to approx. 0.6.

Select units of measurement:

OD, cells/ml.

With units OD selected the results output are OD values. If cells/ml was selected two further parameters are displayed (Factor and Multiplier).

The measured absorbance in these turbid samples is due to light scattering, and not the result of molecular absorption.

A calibration curve can be determined by comparing measured OD 600 to expected OD 600 determined by using an alternative technique (e.g. microscope slide method).